1. Field of the Invention
The present invention relates to a heat developing apparatus in which a heat processing section to heat develop a heated developing sheet on which a latent image by an exposure is formed, is opened toward the outside of the apparatus by the opening and closing of an opening and closing cover, and particularly to the control technique of the rising temperature of the heat processing section.
2. Description of the Related Art
In a plate making image forming apparatus for making a plate-making for printing, or an image forming apparatus to record a medical image such as a Computed Tomography or Magnetic Resonance, an image forming apparatus by using a dry system which forms the image by the heat developing, without conducting the wet processing, is remarked. In such the image forming apparatus, a photosensitive and/or heat sensitive recording material (photosensitive heat sensitive recording material) or film of heat developing photosensitive material (hereinafter, called heated developing sheet) is used, and a latent image formed by irradiating (scanning) the laser beams, is developed by the heat, and the image is formed. In the image forming apparatus by such the dry system (hereinafter, called heat developing apparatus), not only the image formation can be attained in a shorter time than the wet processing, but a problem of waste solution processing can also be eliminated, and it is fully presumed that the demand will be increased in the future.
Conventionally, this heat developing apparatus is structured, as a main structure, by a conveyer to supply and convey the heated developing sheet after the latent image formation, preliminary heating section to preliminarily heat, main heating section corresponding to a developing section, gradually cooling section to gradually cool the heated developing sheet which is heat developed by the main heating section, and exhaust section to exhaust the gas generated in the apparatus.
The preliminary heating section is structured in such a manner that a plurality of roller units each of which is structured by a heating roller and a conveying roller, are arranged at an equal interval along the conveying direction of the heated developing sheet. The closer a heating roller is to the main heating system, the higher the heating temperature of the heating roller is, and it is set so that, when the heated developing sheet passes the heating roller closest to the main heating section, the temperature of the heated developing sheet is increased to the developing temperature.
The main heating section is structured in such a manner that a plurality of heating units in which a heat plate and a plurality of conveying rollers and sub-heater are arranged, are arranged along the conveying direction of the heated developing sheet. The heated developing sheet is nipped by the heat plate and the conveying roller, and heated at the developing temperature while being conveyed, and advances to the gradually cooling section side.
The gradually cooling section is structured in such a manner that a slanting section is arranged between a sending roller structured by a pair of conveying rollers, and a delivery roller structured by a pair of conveying rollers. The falling speed of the heated developing sheet after development is adjusted in the gradually cooling section by the sending roller and the delivery roller, and the sheet is gradually cooled to about the room temperature at a predetermined cooling speed.
According to the heat developing apparatus structured as described above, because the apparatus is provided with the preliminary heating section and the gradually cooling section, the quick temperature change (quick temperature rise and down) is not caused on the heated developing sheet, and the developing is smoothly and surely conducted. That is, in the preliminary heating section, at the temperature difference by which the developing unevenness due to the deformation of the substrate of the heated developing sheet is not generated, the sheet is preliminarily heated to the developing temperature in stages. Accordingly, in the main heating section, because the temperature of the sheet is not instantaneously raised from a low temperature to the developing temperature, the generation of the developing unevenness due to the large deformation of the substrate is suppressed. Then, because the gradually cooling is conducted in the gradually cooling section, the generation of the wrinkle or lowering of the image quality due to the quick temperature down is prevented.
In the heat developing apparatus, at the time of start from the unused condition, or the start after return from the jam, the quick responsibility of the startup temperature and the temperature stability is required. However, in an ordinary PID (Proportional, Integral, Derivative) control or ON/OFF control, the temperature of the heater and the portion near the heater is stabilized soon, but the response of the temperature of the portion apart from the heater is slow. Therefore, in order to raise the temperature to the predetermined temperature soon, it is conducted that the temperature of the heater is raised to the higher temperature than the stable temperature once. In the temperature control method in this case, the raised temperature and the raising time are controlled amounts.
However, conventionally, at the time of startup, the temperature drop amount at the time of startup is detected by one temperature sensor, and corresponding to that, the control amount is set. Because of that, the temperature control method can cope with the temperature around the detecting portion, however, to the temperature of the other portions, it is not always the optimum control amount. For example, even when the apparatus is started in the same manner, the two kinds of temperature drops cannot be distinguished from each other. That is, a case where the start is a start from the condition that the opening and closing cover is closed (power source is turned off), or a case where the operating apparatus is stopped once when the cover is opened by the jam, and after the restore from the jam, the apparatus is started again, are not distinguishable. Accordingly, in the latter case, when the controlled amounts are set to the same as in the former case, the portion at which the temperature is too high is generated.
In view of the foregoing, the present invention is attained, and the object of the present invention is to provide a temperature control method of a heat developing apparatus by which, for various operating conditions of the apparatus, the optimum temperature control amounts can be determined, and a heat developing apparatus, and thereby, to secure the quick responsibility of the startup temperature.
A temperature control method of the heat developing apparatus according to the first aspect of the present invention to attain the above object, is a temperature control method of a heat developing apparatus in which a heat processing section to conduct the heat developing on a heated developing sheet on which a latent image by the exposure is formed, is opened toward the apparatus outside by an opening and closing motion of an opening and closing cover, wherein a temperature detection is conducted by a first sensor which is arranged in the vicinity of a conveying path of the heated developing sheet of the heat processing section and to be exposed to the outside of the apparatus when the opening and closing cover is opened; simultaneously, a temperature detection is conducted by the second sensor which is arranged in the heat processing section and to be kept unexposed to the outside of the apparatus when the opening and closing cover is opened; and an optimum combination of a control variable and a control amount is selected from predetermined combination of control variables and control amounts corresponding to the combination of each temperature detected by the first and the second sensor, and the temperature control of the heat processing section is conducted at the time of the start of the apparatus operation according to the selected optimum control variable,.
In this temperature control method of the heat developing apparatus, the temperature is detected by the first sensor provided in a portion where temperature change is large, and the second sensor provided in a portion where temperature change is small. Further, the optimum control variable is previously stored corresponding to the combination of each temperature by the first sensor and the second sensor, and at the time of the start of the apparatus operation, the optimum control variable is selected corresponding to each temperature detected by the first and the second sensors, and the temperature control of the heat processing section is conducted by the optimum control variable. Thereby, the discrimination of the temperature lowering condition in the various using condition which cannot be conducted by the temperature detection by one sensor can be conducted, and the setting of the control variable can be exactly conducted, and the delay to the temperature stabilization is hardly generated. Particularly, because the opening and closing condition and the closing condition of the opening and closing cover can be discriminated, the optimum control variable can be exactly obtained, and the temperature of the heat processing section can be quickly stabilized.
A temperature control method of the heat developing apparatus according to the second aspect of the present invention is similar to the temperature control method of the heat developing apparatus of the first aspect of the present invention, except that the optimum combination of control variables and control amounts are selected based on a combination of temperature drops measured by the first and second sensors.
According to the temperature controlling method of the second aspect, it is possible to detecting the temperature drop condition to further enable an apparatus with said method to more accurately determine the status under which the apparatus is working, eventually enabling rapid stabilization of the temperature in the heat processing unit.
A heat developing apparatus of the third aspect of the present invention is a heat developing apparatus which is provided with a heat processing section to heat develop a heated developing sheet on which the latent image is formed by an exposure, and the opening and closing cover to expose the heat processing section toward the outside of the apparatus, wherein the heat developing apparatus has: a first sensor to be disposed in the vicinity of a conveying path of the heated developing sheet of the heat processing section and to be exposed to the outside of the apparatus when the opening and closing cover is opened; the second sensor to be arranged in the heat processing section and to be kept unexposed to an outside of the apparatus when the opening and closing cover is opened; a memory means to memorize combinations of predetermined control variables and control amounts in correspondence with the combination of each temperatures measured by the fist and the second sensor; and a control means to select the combination of optimum control variable and control amount at the time of the start of the apparatus operation corresponding to the combination of each temperature detected by the first and the second sensor, and the heating control of the heat processing section is conducted according to the combination of the optimum control variables and the optimum control amounts which are selected.
In this heat developing apparatus, by the first sensor and the second sensor, the temperature of a portion where temperature change is large when the opening and closing cover is opened, and the temperature of a portion where temperature change is small even when the opening and closing cover is opened, are detected. Then, the combination of the optimized control variables and the optimized control amounts corresponding to respective combinations of the detected temperatures are selected from the memory means by the control means. In the heat processing section, according to the selected control variables and control amounts, the heating control is conducted by the control means. That is, according to the combination of each temperature, the various apparatus conditions can be grasped. Thereby, the temperature can be quickly stabilized by the combination of the optimum control variables and the optimum control amounts, and as the result, the quick responsibility of the startup temperature can be secured.
A heat developing apparatus of the fourth aspect of the present invention is similar with the heat developing apparatus of the third aspect, except that the combination of the optimum control variables and the optimum control amounts are selected based on the combination of the temperature drops measured by the first and second sensors.
According to the apparatus of the fourth aspect of the present invention, various apparatus condition changes can be grasped and the temperature can be stabilized quickly by the combination of the optimum control variables and the optimum amounts selected based on the temperature drops.
A heat developing apparatus of the fifth aspect of the present invention is characterized in that: the combination of the optimum control variables and the optimum control amounts is a combination of control variables and control amounts by which a heating temperature to each of a plurality of heating bodies existing in the heat processing section is respectively set, corresponding to the combination of the temperature drop amount from the temperature of the heat processing section before the opening of the opening and closing cover to each temperature detected by the first and second sensors at the time of opening of the opening and closing cover.
In this heat developing apparatus, for example, although the temperature lowering amount of the second sensor is small, when the temperature lowering amount of the first sensor is large, it is judged that the heat processing section is opened. The heating means is heating controlled by the combination of control variables and control amounts corresponding to the combination of the temperature drop amount, the heating of the heater is not conducted for which the heating is not necessary, and the minimum necessary heaters are heated and the temperature of the heat processing section is stabilized at a short time.
A heat developing apparatus of the sixth aspect according to the present invention is characterized in that the control variables and control amounts are selected from a previously set table which can be looked up with a combination of the temperature drop amounts detected by the first and the second sensors.
In this heat developing apparatus, when the temperature drop amounts are detected by the first sensor and the second sensor, the combination of optimized control variables and optimized control amounts corresponding to the combination of the temperature drops is instantaneously specified from the table stored in the memory means. Accordingly, it is not necessary that the control variable stored in the table is a control variable having particularly the regularity, and for example, the control variable may be a proper control variable corresponding to respective combinations obtained by the experiment. Further, by storing the data of the combinations of the control variables and the control amounts in the form of the table, the table can be easily diverted to the other apparatus in which the structure of the heat processing section or the opening and closing condition is different, by partially changing the data.
A heat developing apparatus of the seventh aspect according to the present invention is characterized in that the control variable is set by the previously set function to each temperature drop amount detected by the first and the second sensors.
In this heat developing apparatus, when the temperature drop amounts are detected by the first and second sensors, from the function stored in the memory means, the optimized control amounts for predetermined combination of control variables, corresponding to the combination of the temperature drop amounts, is calculated and specified. Accordingly, an amount of the data stored in the table can be reduced, and further, the control variable can be precisely set.